All migrations are run from and stored in the Flatties.Matching.Persistence project.
In order to create and run a migration for a startup project (i.e. Flatties.Matching.WebApi or Flatties.Matching.Application.Tests), you need to invoke the following commands from the Flatties.Matching.Persistence directory:
dotnet ef migrations add InitialCreate --startup-project ../Flatties.Matching.Application.Tests/Flatties.Matching.Application.Tests.csproj
dotnet ef database update --startup-project ../Flatties.Matching.Application.Tests/Flatties.Matching.Application.Tests.csproj
The migration will be applied to the database that the startup project is configured to connect to.